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ACDP CL3 Laboratories

Text in bold denotes additional requirements for Laboratory Containment Level 3 when compared to Laboratory Containment Level 2.

Containment Level 2 is suitable for work with agents in Hazard Group 2. Laboratory personnel must receive suitable and sufficient information, instruction and training in working safely with agents in Hazard Group 2. A high standard of supervision of the work should be maintained.A list must be kept of employees engaged in work with biological agents in Hazard group 3 indicating the type of work done and, where known, the agent(s) to which they are exposed. This must include, as appropriate, a record of exposure (e.g. resulting for accidents and incidents).

1. The laboratory must be separated from other activities in the same building.
2. Access to the laboratory is to be restricted to authorised persons.
3. The laboratory must be maintained at an air pressure negative to the atmosphere (see paragraph 31). Extracted air must be HEPA filtered (or equivalent).
4. The laboratory must be sealable to permit disinfection (see paragraph 28).
5. There must be specified disinfection procedures.
6. Bench surfaces and the floor must be impervious to water, easy to clean and resistant to acids, alkalis, solvents and disinfectants.
7. There must be safe storage of biological agents.
8. There must be an observation window or an alternative so that occupants can be seen.
9. The laboratory must contain its own equipment, so far as is reasonably practicable.
10. Laboratory procedures that may give rise to infectious aerosols must be conducted in a microbiological safety cabinet, isolator or other suitable containment.
11. An incinerator must be accessible for the disposal of animal carcasses (see paragraph 27).
12. Personal protective equipment, including protective clothing, must be:
    (a) stored in a well-defined place;
    (b) checked and cleaned at suitable intervals;
    (c) when discovered to be defective, repaired or replaced before further use.
13. Personal protective equipment which may to contaminated by biological agents must be:
    (a) removed on leaving the working area;
    (b) kept apart from uncontaminated clothing and equipment;
    (c) decontaminated and cleaned or, if necessary, destroyed.
14. There should be adequate space (24m³) in the laboratory for each worker.
15. The laboratory door should be closed when work is in progress and locked when the room is unoccupied. A biohazard sign should be posted at the entry to the laboratory.
16. Side or back fastening laboratory gowns or coats should be worn in the laboratory and removed on leaving it. These should be autoclaved before being sent for laundering. Additional protection, for example, gloves and plastic aprons, should also be made available.
17. Eating, chewing, drinking, smoking, taking medication, storing food and applying cosmetics should be forbidden in the laboratory.
18. Mouth pipetting should be forbidden.
19. A Class I or Class III microbiological safety cabinet (BS 5726: 1992 or unit with equivalent protection factor or performance) is the most suitable for laboratory procedures likely to give rise to infectious aerosols. In some cases, equipment which is designed to contain aerosols at source may be in use but its integrity in this respect should be verified before it is accepted as an alternative to containment of the work in a safety cabinet. Where protection of the work is essential (for example cell cultures are in use) and the route of transmission of the agent concerned is primarily percutaneous, a Class II safety cabinet may be used provided that it can be shown to offer operator protection to the standard of BS 5726 under the conditions of use.
20. Safety cabinets must exhaust through a HEPA (High Efficiency Particulate Absorption) filter or equivalent to the outside air or into the laboratory air extract system, and in other respects such as siting, performance in use, protection factor and air filtration, should comply with the performance specifications detailed in BS 5726: 1992. If laboratories are faced with a major problem because of difficulties in arranging for the cabinet to exhaust to open air, recirculation of exhaust air through two HEPA filters in series may, in exceptional circumstances, be considered as an alternative. In this case, the maintenance of a continuous airflow into the laboratory during work with infectious material will be of particular importance (see paragraph 31) and such an option should not be adopted without prior consultation with HSE.
21. A wash basin should be provided near the exit of the laboratory. Taps should be of a type that can be operated without being touched by hand.
22. Gloves should be worn for all work with infective materials and hands should be washed before leaving the laboratory. Gloves should be washed or preferably removed before touching items that will be touched by others not similarly protected, for example telephone handsets, paperwork. Computer keyboards and, where practicable, equipment controls should be protected by a removable flexible cover that can be disinfected.
23. An autoclave for the sterilisation of items to be recycled and/or waste materials should preferably be situated within the laboratory, but if this is not practicable, then one should be readily accessible in the laboratory suite.
24. Materials for autoclaving should be transported to the autoclave in robust containers without spillage.
25. There should be means for the safe collection, storage and disposal of contaminated waste.
26. Contaminated waste should be suitably labelled before removal for incineration.
27. "Access to an incinerator" - see paragraph 11, may be taken to mean an incinerator at another site but whether local or distant, carcasses for incineration must be transported in secure containers.
28. COSHH requires that the Containment Level 3 laboratory be sealable to permit disinfection. While the definition of "disinfection" may be widely interpreted, in practice, it may be necessary, subject to the assessment of risk, to decontaminate by fumigating the accommodation when, for example, a spillage has occurred or when maintenance work is to be carried out.
29. Where it is not reasonably practicable for the laboratory to contain its own equipment, for example, a deep-freezer, material should be transported without spillage in properly labelled robust containers which should be opened only in Containment Level 3 accommodation.
30. All accidents and incidents should be immediately reported to and recorded by the people responsible for the work or other delegated people.

Achieving an inward flow of air

31. COSHH REQUIRES that a Containment Level 3 laboratory is maintained at an air pressure negative to atmosphere. "Atmosphere" in this context may be taken to mean the external air and/or other parts of the laboratory suite or building. In effect, this means arranging engineering controls such that a continuous inward airflow into the laboratory is maintained but this is necessary gene rally only when work with biological agents is actually in progress. Provision should be made for comfort factors, ie supply of fresh air, temperature control.
32. One of the following means should be adopted to achieve the inward flow of air:
    (a) extracting the laboratory air through independent ducting to the outside air through a HEPA filter (or equivalent);
    (b) extracting the laboratory air to the outside air with a fan and HEPA filter (or equivalent) sited in a wall or window of the laboratory;
    (c) ducting the exhaust air from the microbiological safety cabinet to the outside air through a HEPA filter (or equivalent); or
    (d) a safe variation of these methods.
33. Whichever method is used, the requirement of COSHH Regulation 9 referring to maintenance, examination and test of control measures and specifically to "local exhaust ventilation" must be observed. This means that HEPA filters and their fittings and seals must be thoroughly examined and tested at intervals not exceeding 14 months. In practice, depending on the frequency of use, these tests are commonly carried out at shorter intervals, for example, six monthly.
34. In laboratories with a mechanical air supply system, the supply and extract airflows should be interlocked to prevent positive pressurisation of the room in the event of a failure of the extract fan. The ventilation system should also incorporate a means of preventing reverse airflows. The design of systems to achieve the required inward flow of air should aim for simplicity to avoid the chances due to over complicated control mechanisms. Instrumentation should be relevant and sensitive to the factors that contribute to safety. Engineers should be asked to consider as a priority the safety features of the room when arranging heating and ventilation and the disposal of heat generated by equipment. In particular, the influx of cold air and the siting of ventilation outlets and extracts can have a significant effect on the performance of safety cabinets.

[Source: abstracted from Categorisation of biological agents according to hazard and categories of containment, ACDP. 4th ed, 1995. (Note- this document has been superseded by: The management, design and operation of microbiological containment laboratories. ACDP. 2001.)]